Atherosclerosis is a disease which results in narrowed arteries and decreased blood flow. The arteries become narrowed because of a build up of plaques in their inner walls. Plaques consist of a mixture of substances including cholesterol, fat, fibrous tissue, clumps of platelets and sometimes calcium.
Atherosclerosis begins early in life, but generally causes no symptoms until middle or old age. This is because it takes many years for plaques to develop and because normal arteries are much larger than they need to be. Only after an artery becomes very narrowed will blood flow be diminished enough to cause symptoms. When atherosclerosis affects arteries supplying blood to the heart, patients experience angina and claudication.
Hyperlipidaemia is a risk factor of atherosclerosis. In general, individuals with an increased level of cholesterol are prone to develop or have already developed atherosclerosis. However, although some individuals may not have an increased level of cholesterol, it does not necessarily mean that they do not suffer from atherosclerosis. Hyperlipidaemia has little diagnostic value in cardio-vascular pathology since only 10-20% of the total patients with clinical complications of atherosclerosis demonstrate an elevated level of cholesterol in their plasma.